Keyboard electronic music instrument with step-wise variable volume control responsive to key-touch

ABSTRACT

A keyboard electronic musical instrument having a volume control arrangement responsive to each key-touch on the keyboard of the instrument, the volume control arrangement comprising an analogue voltage generator for producing an analogue voltage in proportion to the magnitude of a key depressing force, a stepwise converter for producing one of several different digital voltages stepwisely responsive to the analogue voltage, and a tone level control circuit for varying in accordance with the digital voltage from the stepwise converter, the level of a tone signal delivered from a tone signal generator upon selective depression of any key on the instrument keyboard, whereby musical tones emanated from the instrument have their volumes varied in a discontinuous digital manner with the magnitude of the key depressing speed.

United States'Patent [191,

O'kamoto I June 25, 1974 [5 KEYBOARD ELECTRONIC MUSIC 3,626,076 12/1971 Uchiyama 84/1.23 INSTRUMENT 3221333 111335 211 321152;

1 1 3C 1 i VARIABLE VOLUME CONTROL 3,697,662 10/1972 Adachi 84/1.13 RESPONSIVE To KEY-TOUCH 3,715,445 2/1973 Kniepkamp 84/1.13 [75 Inventor; Shimaii ()kamoto, Hamamatsu, R27,0l5 12/1970 Dijksterhuis et a1 84/126 Japan i Prima Examiner-Richard B. Wilkinson [73] Assxgnee: Nqfpon Gakk' sum P Assistr r ExaminerStan1ey J. Witkowski F Hamamatsu'shl Attorney, Agent, or FirmFlynn & Frishauf shizuoka-ken, Japan [22] Filed: May 11, 1973 [57] ABSTRACT PP 359,362 A keyboard electronic musical instrument having a volume control arrangement responsive to each key- [301 Foreign Application Priority Data touch on the keyboard of the instrument, the volume 1 control arrangement comprising an analogue voltage May 11, 1972 Japan 47-46804 gfinerator for producing an analogue voltage in portion to the magnitude of a key depressing force, a

1 t f 'P i l l 1 13 ent digital voltages stepwisely responsive to the ana- 1 0 l 7 'logue voltage, and a tone level control circuit for varying in accordance with the digita] voltage from the 56 R f d stepwise converter, the level of a tone signal delivered I I e erences from a tone signal generator upon selective depression UNITED STATES PATENTS of any key on the instrument keyboard, whereby musi- 3,534,144 10/1970 Ring 84/101 cal tones emanated from the instrument have their 3,571,481 3/1971 Adachi 4. 84/1.13 volumes varied in a discontinuous digital manner with the magnitude of the key depressing peed 3,626,074 12/1971 Hiyamam; 84/l.0l 3,626.075 l2/1971 Hiyama 84/1.l3 8 Claims, 8 Drawing Figures TONE TONE S TONE SIGNAL LEVEL COLORNG GENERATORS CONTROL FILTERS KEYERS l i a I I -H, STEPWISE --42 )1. 3 GENERATORS 311 312 J 31in ..s.

1 KEY-TOUCH -41 1 RESPONSIVE ANALOGUE VOLTAGE GENERATORS PATENTEDmzs 19m SHEET 2 UF 3 I I I 33 9 3T TONE TONE I TONE SIGNAL LEVEL COLOR,NG GENERATORS CONTROL F'LTERS KEYERS 2:2 I STEPWISE 4 H I GENERATORs 2 M 311 312 F J 3In I I KEYTOUCH--4{ F I G, 4 RESPONSIVE ANALOGUE VOLTAGE GENERATORs I\7 w L3 H A -J uJ L2 F I G. 5 I"- -KEY DEPRESSING FORCE I LI I I L R4 1 I ---Q4 R3 I I TO TONE FROM TONE i J GENERATOR 34 bi #ERE Q g 32 42 I 102 RT I I I r l i w Jl I llllllll I THRESHOLD I 311312 I Bin: CIRCUIT I I KEY-TOUCH I THRESHOLD I F G 6 RESPONSIVE CIRCUIT I ANALOGUE I I VOLTAGE THREsHOLO I GENERATOR CIRCUIT 2H I THREsHOLO I CIRCUIT mmmms m4 3.819.843

SHEET 3 0F 3 FROM TONE SIGNAL THRESHOLDQGAI' GENERATOR 34 T CIRCUIT A 311 3H2 31 THRESHOLD 3 43 KEY-TOUCH RESPONSIVE R ANALOGUE VOLTAGE GENERATOR THRESHOLD OH 3 CIRCUIT 2 NR 41 THRESHOLD CIRCUIT I TO TONE COLORING T FILTER 35 61 FROM TONE SIGNAL GENERATOR 34 31 3i l 31 U ANALOGUE VOLTAGE CONVERTER GENERATOR OH TO TONE COLORING FILTER 35 KEYBOARD ELECTRONIC MUSIC-INSTRUMENT wrrn STEP-WISE VARIABLE VOLUME CONTROL RESPONSIVE T KEY-TOUCH BACKGROUND OF THE INVENTION The present invention relates to a keyboard electronic musical instrument and more particularly to a novel type of volume control arrangement. With a keyboard musical instrument such as a piano, a prominent difference arises in the volumes of produced musical tones between when a key on the keyboard is strongly or quickly depressed and when a key is lightly or slowly depressed. In contrast, with a conventional keyboard electronic musical instrument such as an electronic organ, when any key on the instrument keyboard is depressed, it is only designed to cause a key switch associated therewith to be actuated and a tone signal from a tone signal generator associated therewith to be conducted tO a loudspeaker through the succeeding circuitry including tone coloring filters, an expression control and an amplifier, thereby to emanate from the loudspeaker a musical sound or tone having a desired tone color. That is, the volume of musical tones from such conventional instrument is controlled only by means of an expression control manipulated by a players foot.

Accordingly, key depression, whether effected quickly or slowly, does not give rise to any change in the volume of produced musical tones, namely, a mere key operation has failed to produce musical tones resembling those of a piano.

in view of the above-mentioned situation, there has recently been developed a tone volume control device, such as the one shown in FIG. 1 which is so designed as to control, upon selective depression of a key, the volume of musical tones emanated from the instrument in response to the magnitude of the key depressing force or speed.

In FIG. 1, tone signals from tone signal generators 14 are respectively fed to corresponding tone level control keyers which are normally kept nonconductive, and when any of plural keys 11,, 11 ll juxtaposed on a keyboard 12 in the order of musical notes is depressed, the corresponding one of the key-touch responsive analogue voltage generators 17 generates an analogue voltage representing the force with which the key is depressed. The analogue voltage thus obtained is supplied to the corresponding one of the tone level control keyers 15' so as to cause it to be made conductive. Consequently, a tone signal generated by one of the tone signal generators 17 which corresponds to the depressed key is then conducted through the conducting tone level control keyer 15 to a line 16, its level being determined in response to the analogue voltage delivered from the key-touch responsive analogue voltage generator l7 constructed as hereinafter described.

The key-touch responsive analogue voltage generator 17, though only one corresponding to a given key 11 is shown in FIG. 2, has a permanent magnet or magnetic material 21 and a coil 22 wound around a core 23 so arranged under the key 11 as to progressively approach (or level) each other as the key 11 is depressed for perfon'nance. Various practical arrangements of the permanent magnet 21 and the coil 22 are detailed in the Us. Pat. No. 3,705,254 issued to Amano.

The coil 22 has the one end connected to the ground and the other end connected via a rectifier constructed, eg of a diode 24 of the indicated polarity to the control electrode or gate of a field eflect transistor Q constituting the aforesaid tone level control keyer 15. The field effect transistor Q has its drain-source path or conduction channel connected between the line 16 and a tone signal generator 14 corresponding to the key 11. The gate of the field effect transistor Q is also con nected to ground via a capacitor C as well as a series circuit of a resistor R and a normally closed key switch 25 which is opened when the key 11 is operated.

When the key 11 is depressed, the key-touch responsive analogue voltage generator 17 constructed as mentioned above act to induce across the coil 22 and electromotive force or a pulsating voltage whose level varies with the rate of changes with time in the amount of a magnetic flux penetrating the coil 22, namely, the

speed or velocity at which the key 11 is depressed.

The pulsating voltage thus obtained is rectified by the diode rectifier 24 and is then charged in the capacitor C. The voltage charged in the capacitor C is applied to the gate of the field effect transistor Q so as to vary an internal resistance prevailing across its drain and source. As a result, the resultant tone signal appearing at the line 16 is finally emanated through the succeeding circuits including a tone coloring filters 18,.an expression control 13 and an amplifier 19 from a loudspeaker 20 as a musical tone bearing a desired color and having its volume controlled in accordance with the magnitude of the key depressing force. When the key 11 is released and in consequence the key switch 25 is closed, the voltage of the capacitor C is discharged through the resistor R and the closed key switch 25 to be ready for next operation.

However, the prior art keyboard electronic musical instrument of the above-mentioned construction has the drawback that the volume of its musical tones minutely varies to an extent indistinguishable by a player other than .a well-skilled player, because the volume change takes place in a Continuous analogue manner in the form of curve A, B or C shown in FIG. 3 in accordance with the magnitude of a key depressing force or speed.

It is therefore the object of this invention to provide a keyboard electronic musical instrument with a volume control, particularly suitable for a beginner, which is capable of varying with the key depressing force in a discontinuous digital manner the volume of musical tones produced upon selective depression of any key on the keyboard. In this specification and in the appended claims, the term digital means stepwise discontinuity of values, and not digital numerical representation of values.

SUMMARY OF THE INVENTION The keyboard electronic musical instrument according to the invention is characterized in that it is designed to provide akey-touch responsive volume control arrangement comprising a key-touch responsive analogue voltage generator producing, upon selective depression of any key on the instrument keyboard, an analogue voltage in proportion to the magnitude of the key depressing force; a stepwise converter coupled with the analogue voltage generator and producing one of a plurality of different digital voltages stepwisely responsive to'the analogue voltage; and a tone level control circuit coupled with the stepwise converter and with a tonesignal generator which generates a tone signal of a predetermined pitch so as to vary the level of the tone signal generated by the tone signal generator in response to that of the digital voltage derived from the stepwise converter.

The keyboard electronic musical instrument with the key-touch responsive volume control thus arranged has the advantage that it is particularly suitable for a beginner, because the volume of musical tones emanated from the instrument varies stepwise in a discontinuous digital manner with the magnitude of the force or speed at which any key on the instrument keyboard is depressed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a schematic block circuit diagram of a prior art keyboard electronic musical instrument;

FIG. 2 is a practical circuit arrangement of the keytouch responsive analogue voltage generator shown in FIG. 1;

FIG. 3 is a curve diagram illustrating the relationship of a key depressing force versus a tone level for the instrument shown in FIG. 1;

FIG. 4 is a schematic block circuit diagram of a keyboard electronic musical instrument in accordance with the invention;

FIG. 5 is a curve diagram illustrating the relationship of a key depressing force versus a tone level for the instrument in accordance with the invention;

FIG. 6 is a practical arrangement of the stepwise converter and the tone level control keyer shown in FIG. 4; and

FIGS. 7 and 8 are different practical arrangements of the stepwise converter and the tone level control keyer shown in FIG. 4.

PREFERRED EMBODIMENT OF THE INVENTION FIG. 3 shows a schematic block circuit diagram of a keyboard electronic musical instrument embodying the invention.

When any of a plurality of keys 3],, 31 31, arranged on a keyboard 32 in the order of musical notes is selectively depressed during performance, a keyboard electronic musical instrument heretofore put to practical application such as an electronic organ is generally designed to emanate musical tones of a desired tone color by conducting a tone signal of a predetermined pitch generated from one tone signal generator 34 associated with the depressed key to a loudspeaker 37 through the succeeding circuits including tone coloring filters 35, an expression control 33 and an amplifier 36.

The keyboard electronic musical instrument of this invention is characterized in that there is further provided a key-touch responsive volume control arrangement of the later described construction which is adapted to vary stepwise in a discontinuous digitalmanner the level of a tone signal derived from the tone signal generator 34, namely, the volume of musical tones emanated from the instrument in response to the magnitude of the force with which any key on the keyboard 32 is depressed.

The key-touch responsive volume control arr-angement comprises key-touch responsive analogue voltage generators 41 each arranged as illustrated in FIG. 2 and each generating an analogue voltage 51 as shown in FIG. 5 with its voltage level controlled in proportion to the magnitude of the key depressing force when any key on the keyboard'32 is depressed; stepwise converters 42 coupled with the analogue voltage generators 41 and each producing a digital voltage stepwisely in response to the analogue voltage delivered from the keytouch responsive analogue voltage generators 41; and tone level control keyers 43 coupled with the tone signal generators 34 and with the stepwise converters 42 so as to stepwisely vary the level of a tone signal generated by one of the tone signal generators 34 which corresponds to the depressed key in response to one of different digital voltage levels L L L and L as shown in FIG. 5 which is delivered from the stepwise converters 42;

FIG. 6 is a practical arrangement of the stepwise converters 42 and the tone level control keyers 43 shown in FIG. 4.

The stepwise converters 42 each comprise a plurality of, e.g. four threshold circuits (Schmitt circuits) 61, 62, 63 and 64 having their inputs connected jointly to the output of the corresponding one of the analogue voltage generators 41 and biased at different threshold levels. This is the first threshold circuit 61 is designed to be made conductive and produce an output when an analogue voltage supplied thereto from the corresponding analogue voltage generator 41 exceeds a first lowest level; the second threshold circuit 62 is rendered conductive when the analogue voltage rises above a higher second level than the first level; the third threshold circuit 63 is brought to a conducting state when the analogue voltage increses over a higher third level than the second level; and the fourth threshold circuit 64 is set at a conducting state when the analogue voltage reaches a highest fourth level exceeding the third level. The tone level control keyers 43 each comprise four normally open-circuit or nonconducting type field effect transistors Q1, Q2, Q3 and 04 having their gates separately connected to the corresponding outputs of the threshold circuits 61 to 64.

The sources (or drains) of the field effect transistors O1 to Q4 are jointly connected to the tone generators 34 and the drains (or courses) thereof are connected via the corresponding resistors R1, R2, R3 and R4 jointly to the tone coloring filter 35.

The operation of the keyboard electronic musical instrument according to the invention will now be described with reference to FIGS. 4 to 6.

Firstly, when any key on the keyboard 32 is depressed very slowly or lightly, only the first threshold circuit 61 is rendered conductive while the remaining threshold circuits 62 to 64 remain nonconductive, causing only the first field effect transistor 01 included in the tone level control keyer 43 to be fired or rendered conductive and giving out a tone signal'at the lowest voltage level L1 as shown in FIG. 5.

Secondly, when .the key is depressed a little more quickly than in the first case, the first and second threshold circuits 61 and 62 are made simultaneously conductive so as to bring the first and second field effect transistors 01 and O2 to an operative state, thereby giving out a tone signal at the second voltage level L2.

Thirdly, when the key is depressed still more quickly, the first to third threshold circuits 61 to 63 are simultaneously fired so as to cause the first to third field effect transistors O1 to O3 to be rendered conductive, thereby producing a tone signal having the third voltage level L3.

Last, when the key is depressed very strongly or rapidly, all the threshold circuits 61 to 64 and in consequence all the field effect transistors Q1 to 04 are simultaneously fired, producing a tone signal having the highest voltage L4.

As a result, it will be apparent to those skilled in the art that the volume of musical sounds emanated from the instrument is varied in a discontinuous digital manner as shown in FIG. 5 in response to the magnitude of the key depressing force.

A wide variety of volume changes can be attained by suitably selecting the threshold levels of the threshold circuits 61 to 64 and/or the resistances of the resistors R1 to R4 included in the tone level control keyer 43.

FIG. 7 shows one modification of FIG. 6 where the four field effect transistors 01 to Q4 and resistors Rl to R4 constituting the tone level control keyer 43 are respectively replaced by a single bipolar transistor Q11 and a single resistor R1]. The transistor Oil has its base connected in common to the outputs of the threshold circuits 6] to 64 and its emitter-collector path or current conduction path connected via the resistor Rll between the tone generators 34 and the tone coloring filters 35.

FIG. 8 is a further modification of FIG. 7 where the threshold circuits 61 to 64 collectively constituting the stepwise converter 42 are replaced by an analogue-todigital converter 71.

The modifications shown in FIGS. 7 and 8 can be operated in the same manner, and display the same effect, as the aforesaid embodiment.

What is claimed is:

1. ln a keyboard electronic musical instrument comprising a keyboard including a plurality of keys arranged side by side, tone signal generators each generating a tone signal of a predetermined pitch, and a sound reproducing system coupled to said tone signal generators, the sound reproducing system including tone coloring filters receiving the tone signals and a loudspeaker means coupled to the tone coloring filters for delivering the tone signal generated by said tone signal generators as a musical tone with a desired tone color,

the improvement wherein there is further provided a volume control arrangement which comprises:

a key-touch responsive analogue voltage generator coupled to said keyboard and producing an analogue voltage in proportion to the magnitude of the force with which any of said plurality of keys constituting said keyboard is selectively depressed;

a stepwise converter coupled to said analogue voltage generator and producing an output signal 6 which is stepwisely responsive to said analogue voltage generated thereby; and a tone level control circuit coupled to said stepwise converter and to said tone signal generators to vary the steady state level of the tone signal generated by said tone signal generators in accordance with the level of the output derived from said stepwise converter.

2. A keyboard electronic musical instrument as claimed in claim 1 wherein said stepwise converter comprises a plurality of threshold circuits having their inputs connected jointly to the output of said analogue voltage generator and biased at different threshold levels; and said tone level control circuit comprises a plurality of active circuit elements having their control electrodes connected separately to the outputs of said threshold circuits and their current conduction paths jointly coupled through individual resistors between said tone signal generators and said sound reproducing system.

3. A keyboard electronic musical instrument as claimed in claim 2 wherein said active circuit elements each comprise a field effect transistor.

4. A keyboard electronic musical instrument as claimed in claim 1 wherein said stepwise converter comprises a plurality of threshold circuits having their inputs connected jointly to the output of said analogue voltage generator and biased at different threshold levels; and said tone level control circuit comprises an active circuit element having its control electrode connected in common to the outputs of said threshold circuits and its current conduction path coupled between said tone signal generators and said sound reproducing system.

5. A keyboard electronic musical instrument as claimed in claim 4 wherein said active circuit element comprises a bipolar transistor.

6. A keyboard electronic musical instrument as claimed in claim 1 wherein said stepwise converter comprises an analogue-to-digital converter having its input coupled with the output of said analogue voltage generator, and said tone level control circuit comprises an active circuit element having its control electrode coupled to the output of said analogue-to-digital converter and its current conduction path coupled between said tone signal generators and said sound reproducing system.

7. A keybarod electronic musical instrument as claimed in claim 6 wherein said active circuit element comprises a bipolar transistor.

8. A keyboard electronic musical instrument as claimed in claim 1 wherein said tone level control circuit is coupled to the output of said stepwise converter and is coupled between the output of said tone signal generators and said sound reproducing system. 

1. In a keyboard electronic musical instrument comprising a keyboard including a plurality of keys arranged side by side, tone signal generators each generating a tone signal of a predetermined pitch, and a sound reproducing system coupled to said tone signal generators, the sound reproducing system including tone coloring filters receiving the tone signals and a loudspeaker means coupled to the tone coloring filters for delivering the tone signal generated by said tone signal generators as a musical tone with a desired tone color, the improvement wherein there is further provided a volume control arrangement which comprises: a key-touch responsive analogue voltage generator coupled to said keyboard and producing an analogue voltage in proportion to the magnitude of the force with which any of said plurality of keys constituting said keyboard is selectively depressed; a stepwise converter coupled to said analogue voltage generator and producing an output signal which is stepwisely responsive to said analogue voltage generated thereby; and a tone level control circuit coupled to said stepwise converter and to said tone signal generators to vary the steady state level of the tone signal generated by said tone signal generators in accordance with the level of the output derived from said stepwise converter.
 2. A keyboard electronic musical instrument as claimed in claim 1 wherein said stepwise converter comprises a plurality of threshold circuits having their inputs connected jointly to the output of said analogue voltage generator and biased at different threshold levels; and said tone level control circuit comprises a plurality of active circuit elements having their control electrodes connected separately to the outputs of said threshold circuits and their current conduction paths jointly coupled through individual resistors between said tone signal generators and said sound reproducing system.
 3. A keyboard electronic musical instrument as claimed in claim 2 wherein said active circuit elements each comprise a field effect transistor.
 4. A keyboard electronic musical instrument as claimed in claim 1 wherein said stepwise converter comprises a plurality of threshold circuits having their inputs connected jointly to the output of said analogue voltage generator and biased at different threshold levels; and said tone level control circuit comprises an active circuit element having its control electrode connected in common to the outputs of said threshold circuits and its current conduction path coupled between said tone signal generators and said sound reproducing system.
 5. A keyboard electronic musical instrument as claimed in claim 4 wherein said active circuit element comprises a bipolar transistor.
 6. A keyboard electronic musical instrument as claimed in claim 1 wherein said stepwise converter comprises an analogue-to-digital converter having its input coupled with the output of said analogue voltage generator, and said tone level control circuit comprises an active circuit element having its control electrode coupled to the output of said analogue-to-digital converter and its current conduction path coupled between said tone signal generators and said sound reproducing system.
 7. A keybarod electronic musical instrument as claimed in claim 6 wherein said active circuit element comprises a bipolar transistor.
 8. A keyboard electronic musical instrument as claimed in claim 1 wherein said tone level control circuit is coupled to the output of said stepwise converter and is coupled between the output of said tone signal generators and said sound reproducing system. 